Jet propulsion drive for watercraft

ABSTRACT

AN UPRIGHT HOUSING IS PROVIDED AT THE REAR END OF A WATERCRAFT AND HAS A CROSS-SECTIONAL OUTLINE RESEMBLING A SYMMETRICAL TRAPEZIUM. THE NARROWEST SIDE OF THE HOUSING FACES OPPOSITELY THE INTENDED MOVEMENT OF THE WATERCRAFT AND A PAIR OF SIDEWALLS EXTEND FROM THE NARROWEST SIDE IN THE DIRECTION OF INTENDED MOVEMENT. INLET MEANS ARE PROVIDED FOR ADMITTING WATER INTO THE HOUSING AND OUTLET MEANS ARE INT THE NARROWEST SIDE FOR EXPELLING WATER FROM THE HOUSING. AN EXPELLO VANE IS MOUNTED IN THE HOUSING FOR PIVOTAL MOVEMENT INTERMEDIATE THE RESPECTIVE SIDE WALLS ABOUT AN UPRIGHT AXIS EXTENDIND THROUGH THE HOUSING IN THE REGION OF THE OUTLET MEANS.

Nov. 16, 1971 HARM-HEINRICH MUNTE 3,620,019

JET PROPULSION DRIVE FOR WATERCRAFT Filed Dec. 15, 1969 s Sheets-Sheet 1 Inventor; pupl luff/( fill W7 1971 HARM-HEINRICH MUNTE 3,520,019

JET PROPULSION DRIVE FOR WATERCRAFT Filed Dec. 15, 1969 3 Sheets-Sheet 2 Fig.3

Inventor: m/m HIM/cu Imp?! Nov. 16,1971 HARM-HEINRICH.MUNTE 3,520,019

JET PROPULSION DRIVE FOR WATERCRAFT Filed Dec. 15, 1969 3 Sheets-Sheet 8 DOWNSTREAM UPSTREAM //IIIIIIII/I//I//II/I/// BURDA F/G. 4

I NOZZLE INVENTOR H. MUN TE ATTORNEY United States Patent 01 3,620,019 JET PROPULSION DRIVE FOR WATERCRAFT Harm-Heinrich Munte, Hamburg, Germany, assignor to Blohm & Voss AG, Hamburg, Germany Filed Dec. 15, 1969, Ser. No. 884,796 Claims priority, application Germany, Dec. 18, 1968, P 18 15 313.4 Int. Cl. B63h 11/07 U.S. Cl. 60-221 8 Claims ABSTRACT OF THE DISCLOSURE An upright housing is provided at the rear end of a watercraft and has a cross-sectional outline resembling a symmetrical trapezium.The narrowest side of the housing faces oppositely the intended movement of the watercraft and a pair of sidewalls extend from the narrowest side in the direction of intended movement. Inlet means are provided for admitting water into the housing and outlet means are in the narrowest side for expelling water from the housing. An expello vane is mounted in the housing for pivotal movement intermediate the respective side walls about an upright axis extending through the housing in the region of the outlet means.

BACKGROUND OF THE INVENTION The present invention relates to watercraft, and more particularly to propulsion drive for watercraft. More specifically, the invention relates to a jet propulsion drive for watercraft.

It is already known to provide jet propulsion drive for watercraft, which drives are located at the rear or stern and which comprises housings into which water is caused to enter to thereupon be expelled in the direction oppositely the intended forward movement of the watercraft. The expulsion of jets or streams of water from the housing is effected by means of the moving vane mounted in the interior of the housing and causing, as it moves within the housing, the displacement of Water from the housing and its expulsion in form of a stream of water. The stream depends upon the motion frequency and is intermittent, having a thrust dependent upon the quantity of water expelled per unit of time and the increase in the speed imparted to the thus-expelled water. Basically, these known drives are satisfactory in their operation. It has been found, however, that they cannot be entirely satisfactorily mounted on the watercraft themselves because of various reasons which are well known to those skilled in the art.

SUMMARY OF THE INVENTION It is, accordingly, an object of the present invention to provide an improved jet propulsion drive for watercraft which is not possessed of the aforementioned difiiculties.

It is an object of the present invention to provide such a. jet propulsion drive which provides decided advantages with respect to the manner in which it will be mounted on the watercraft.

A further object of the invention is to provide such a drive which provides for improved water inlet and expulsion conditions.

In pursuance of the above objects, and others which will become apparent hereafter, I provide a jet propulsion drive for watercraft which, briefly stated, comprises an upright housing whose cross-sectional outline resembles a symmetrical trapezium and which has a narrowest side facing in the direction oppositely the intended movement of the watercraft and a pair of sidewalls extend iice from the narrowest side in this direction of intended movement. Inlet means is provided for admitting water into the housing and outlet means is provided in the narrowest side for expelling water from the housing. An expeller vane is mounted in the housing for pivotal movement intermediate the respective side walls about an upright axis extending through the housing in the region of the outlet means.

The housing is essentially of prismatic configuration and because its cross-sectional outline, that is its base surface, has the form of a symmetric trapezium with the narrowest side facing oppositely the intended direction of the movement of the watercraft and containing the outlet for the water, with the pivot axis for the vane being located within the cross-sectional outlines of the housing close to the outlet opening, the housing conforms largely to the normal configuration of ships tail sections or sterns. Furthermore, the fiowpath or water from inlet to outlet can take place without significant deflections and an outlet opening is avoided whose size changes during the vane movement. All of this contributes to provide an exceptionally good operating efiiciency for this drive.

Furthermore, because the housing converges in rearward direction, that is away from the direction of movement of the watercraft to which it is to be secured, which convergence of course is true of the interior as well as the exterior, the speed at which water is expelled from the outlet located at the narrowest side of the housing is greater than would otherwise be possible and is therefore excellently suited for high propulsion speeds.

In addition it has been found that it is advantageous that free spaces be left between the vane and the housing walls, that is spaces into which no portion of the vane enters as the vane is moved about its axis. This is advantageous because solid contaminant bodies which may have been aspirated into the housing with incoming water can come to rest in these spaces and will not cause damage to the vane and/or the valves of the drive as would be the case if they were to be inevitably contacted and carried along by the vane. However, in the prior art constructions it has not been easy to provide such spaces, whereas in the construction according to the present invention, such spaces can be readily provided by suitable location of the pivot axis about which the vane pivots.

Furthermore, the speed at which water issues from the outlet of the housing can be further increased by decreasing the cross-sectional area of the outlet opening, simply by having the outlet opening extend only over a portion of the cross-sectional area of the narrowest side of the housing, preferably over the middle portion of the narrowest side.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a diagrammatic illustration showing the principle of the drive according to the present invention;

FIG. 2 is a section taken on the line IIII and illustrating an actual embodiment of the drive according to the present invnetion;

FIG. 3 is a section taken on the line III-III of FIG. 2; and

FIG. 4 is a diagrammatic view of a Borda nozzle which may be used in conjunction with the present invention.

3 DESCRIPTION OF THE PREFERRED EMBODIMENTS Discussing firstly FIG. 1, it will be seen that reference numeral 1 identifies a vane which pivots to and fro about an axis defined by the shaft 2 to which it is secured; and which latter is turned to and fro by a known drive arranged in the watercraft provided with the invention. This axis is upright and the vane pivots within a housing whose interior is identified with reference numeral 3 and whose cross-sectional base outline is determined by the dimensions b-r with the height being identified by the dimension h.

An actual embodiment of the drive according to the present invention is illustrated in FIGS. 2 and 3. As in FIG. 1, the cross-sectional base outline of the housing 9-which latter is generally prismaticresembles a symmetrical trapezium whose narrowest isde 10 faces rearwardly with respect to the intended movement of a watercraft for which the device constitutes the propulsion means. This means, in other words, that for instance in FIG. 2 the direction of forward movement of the watercraft carrying and supplied with the drive of FIGS. 2 and 3, would be towards the right-hand side of the drawing.

The housing 9 is provided in its interior with a substantially plate-like vane 1 which is upright and moves pivotably about the upright shaft 2 defining a pivot axis. The opposite side walls 8 of the housing, which extend forwardly in the direction of intended movement from the narrowest side 10, are provided with apertures, with the aperatures in one of the side walls being controlled by valve flaps 7 and those in the other of the side walls being controlled by valve flaps 7". These flaps open inwardly into the housing to admit water in the direction indicated by the arrows when a suction exists in the chamber which is respectively defined between the vane 1 and the respective side wall 8. In other words, when the vane 1 moves away from one of the side walls 8, the flaps 7 or 7" therein will open, and they will again close when the vane 1 moves towards this particular side wall 8. At the same time, the reverse takes place with respect to the flaps in the other of the side walls.

As the vane 1 moves away from the side wall provided with the flaps 7' as shown in FIG. 2, the flaps 7' open and admit water in the direction indicated by the arrows. At the same time the movement of the vane 1 in the direction of the arrow associated with it towards the other of the side walls 8, it causes the flaps 7" thereof to closethere shown closed in the drawingand expels water confined between this other side wall of the vane 1 in the direction indicated by the arrow rearwardly towards the narrowest side 10 of the housing and out through the outlet opening 6 provided therein. A flap 5 is provided which, in the illustrated embodiment, freely pivots about the shaft 2 and which in FIG. 2 has just been displaced to the position which itis shown to be assuming, by pressure of the water which is being expelled from the interior of the housing 9. In this position it permits expulsion of the water in the chamber which is is lower chamber in FIG. 2the term lower referring here to the position of the chambers on the drawingwhereas it closes the other chamber into which water is entering at this time through the openings which are uncovered by the flaps 7'. The suction which causes opening of the valve flaps 7 of course also aids movement of the flap 5 towards the position which it assumes in FIG. 2.

Of course, when the vane 1 moves in opposite direction about the shaft 2, then the sequence of events will be reversed and water will be expelled through the outlet 6 from the chamber at the other side of the vane 1. The result of the operation of the drive is an intermittent jet of water depending upon the pivoting or oscillating frequency of the vane 1, and whose thrust is proportional to the quantity of water expelled and to the speed increase imported to it. Because of the prismatic configuration of the housing 1, and because of the fact that the narrowest side of the housing 1 faces oppositely the direction of the intended movement, the losses resulting from friction of the water against the outside of the housing, are very small. At the same time, and because water flowing through the arrangement according to the present invention undergoes only minor deflections contrary to know drives of this type, the pumping effectiveness is exceedingly high in the novel drive. Because of the ues of the flap valves 7', 7", and because the vane is almost completely sealed in the housing, an exactly defined expulsion chamber existsdepending upon which side of the vane 1 acts as the expeller surface during the respective stroke and this largely eliminates the customary losses known in the prior art.

It is emphasized that in place of the flap valves 7, 7" it is also possible to use so-called Bordanozzles, which are well known to those skilled in the art. FIG. 4 shows such a nozzle in diagrammatic form, and it will be appreciated that this hydrodynamic valve, as it might be called, has no moving parts but is so configurated as to let water easily stream into the nozzle (downstream flow) and opposite it with only a very low drag coefiicient, while in the reverse direction (upstream flow) the water is checked by the very high drag coefiicient which is an inherent feature of tht nozzle configuration. Thus, water does not flow through in upstream direction.

As evident from FIGS. 2 and 3, there are three 50- called safety spaces 4 remaining in the interior of the housing between the side walls thereof and the vane 1, into which spaces 4 the vane 1 does not enter, that is to portion of the vane 1 will move into these spaces. Thus, any foreign bodies which may have been aspirated into the housing with incoming water, can be retained in the spaces 4 and will not cause damaging of the valves or the vane 1.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of applications differing from the types described above.

While the invention has been illustrated and described as embodied in a jet propulsion drive for Watercraft, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended Within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:

1. A jet propulsion drive for watercraft, comprising an upright housing whose cross-sectional outline resembles a symmetrical trapezium, and having a narrowest side facing in direction oppositely the intended movement of the watercraft and a pair of sidewalls extending from said narrowest side in the direction of intended movement; inlet means for admitting water into said housing; outlet means in said narrowest side for expelling Water from said housing; and an expeller vane mounted in said housing for pivvotal movement intermediate the respective side walls about an upright axis extending through said housing in the region of said outlet means.

2. A drive as defined in claim 1, wherein said narrowest side has a predetermined cross-sectional area, and wherein said outlet opening has a cross-sectional area which is a fraction of said predetermined cross-sectional area.

3. A drive as defined in claim 2, wherein said outlet opening is provided in the center region of said narrowest side.

4. A drive as defined in claim 1, said vane subdividing the interior of said housing into a suction and an expulsion chamber; and further comprising a control flap pivotable about said upright axis and movable between a plurality of operative positions in which it varies the eifective size of said outlet means and determines the flow direction of expelled water jets, and a closure position in which it disrupts communication between said outlet means and said suction chamber.

5. A drive as defined in claim 4; further comprising an upright shaft coincident with and defining said upright axis; and wherein said control flap is mounted on said shaft freely turnable under the influence of water flowing through said housing.

6. A drive as defined in claim 4; further comprising an upright shaft coincident with and defining said upright axis, said control flap being mounted on said shaft for movement between said positions; and arresting means for arresting said control flap in respective ones of said positions at the will of an operator.

7. A drive as defined in claim 1, said inlet means being provided in said side walls and including a plurality of inlet openings; and further comprising valve flaps each associated with one of said inlet openings and operative for uncovering the same and admitting water therethrough into the respective chamber only in response to the presence of a suction force in such chamber.

8. A drive as defined in claim 1, said inlet means being provided in said side walls and including a plurality of inlet openings each constructed so as to constitute a Borda jet.

References Cited UNITED STATES PATENTS 226,931 4/ 1880 Rose -221 884,474 4/1908 Dawson 60221 3,087,302 4/1963 Brown 60221 3,307,358 3/ 1967 Kerandraon 60--221 CLARENCE R. GORDON, Primary Examiner US. Cl. X.R. 

